title: Thermal expansion, phase diagrams and barocaloric effects in (NH(4))(2)NbOF(5).
abstract: The thermal expansion along the a, b and c axes of a (NH(4))(2)NbOF(5) crystal was measured from 120 to 300 K. Anomalies of α(T) associated with previously reported phase transitions Cmc2(1) --> C2 --> 1a were observed along all directions at T(1) = 259.3 K and T(2) = 220.5 K. The analysis of thermal expansion and heat capacity in the frame of the Pippard relations has permitted us to determine the uniaxial pressure derivatives of the transition temperatures dT/dσ(i). The T-σ(i) phase diagrams have shown a tendency for the intermediate phase to disappear at high stress along the b and c axes. Intensive and extensive barocaloric effects near the structural phase transitions were found to be comparable with the caloric parameters of some ferroelectrics, ferromagnets and antiferromagnets.
authors.affiliation: L V Kirensky Institute of Physics, Siberian Division, Russian Academy of Sciences, Akademgorodok, Krasnoyarsk, 660036, Russia. gorev@iph.krasn.ru
authors.forename: Michail
authors.initials: M
authors.lastname: Gorev
authors.forename: Evgeny
authors.initials: E
authors.lastname: Bogdanov
authors.forename: Igor
authors.initials: I
authors.lastname: Flerov
authors.forename: Nataly
authors.initials: N
authors.lastname: Laptash